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MENDELIAN INHERITANCE 2002. Genotype Phenotype Locus Allele Homozygote/ Heterozygote Compound heterozygote Proband. AD AR XLR XLD Not genetic. Mozart’s Piano Concerto in A-major is K ö chel number. A K365 B K450 C K482 D K488 - PowerPoint PPT Presentation
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MENDELIAN INHERITANCE2002
• Genotype• Phenotype• Locus• Allele• Homozygote/ Heterozygote• Compound heterozygote• Proband
A. ADB. ARC. XLRD. XLDE. Not genetic
Mozart’s Piano Concerto in A-major is Köchel number
• A K365• B K450• C K482• D K488• E K491
Clinical vignette
• S G: 20 yo college student– Spontaneous rupture of the common iliac artery– Friable tissues, extensive bleeding– Past history:
• Easy bruising• Lax joints (fingers, elbows, left shoulder)
• D G: 53 yo mother of SG– Spontaneous perforation of the sigmoid colon– Past history
• Easy bruising• No joint laxity• Two normal pregnancies
Laboratory analysis
• Skin fibroblasts: abnormal type III collagen
• COL3A1 DNA analysis: Gly25Val
• Diagnosis: Ehlers-Danlos Syndrome,
Type IV
Pedigree symbols
Autosomal dominant inheritance
• Vertical
• Males and females affected
• Males and females transmit
• Each affected has one affected parent…
NF1
Café-au-lait
Neurofibroma
Lisch Nodules
Neurofibromatosis 1variable expressivity
• Café-au-lait spots
• Axillary freckling
• Lisch nodules
• Cutaneous neurofibromas
• Plexiform neurofibromas
• Scoliosis
• CNS tumors
Marfan syndrome
Marfan ectopia lentis
Marfan life expectancy
Marfan Syndrome variable
expressivity
Incomplete penetrance
AD Erythermalgia
Achondroplasia
What is the risk that this couple’s child will have achondroplasia ?
• A ¼
• B ½
• C ¾
• D 1
• E 0
Achondroplasia mutations in FGFR3
Allelic Heterogeneity
COL3A1 (EDS IV)
Autosomal Recessive
Autosomal Recessive
• Horizontal
• Males and females affected
• Parents of affected are normal
Autosomal recessive
A. ADB. ARC. XLRD. XLDE. Not genetic
Locus Heterogeneity
IV-1,2,3,4,5,6 are all double heterozygotes
congenital deafness
X-linked recessive
X-linked recessive inheritance
• “Diagonal”
• Males affected…
• Transmitted by carrier females
• NO male-to-male transmission
• Daughters of affected males are obligate carriers
X-linked recessive
inheritance
X-linked dominant
X-linked NOT sex-linked
Mitochondrial inheritance
• Mitochondrial DNA– 2 to 100 mitochondria/cell– 5 to 10 chromosomes/mitochondrium– 16.5 kb mt DNA– 37 genes
• Mitochondrial inheritance– Maternal– Heteroplasmy
MERRF
MERRF Pedigree
Heteroplasmy
Myotonic Muscular Dystrophy
• Most common inherited muscular dystrophy of adults
• Muscle wasting—face, neck, distal muscles• Myotonia• Cardiac and smooth muscle affected• Cataracts• Immunoglobulin abnormalities• Insulin resistance• Occ. Mild MR
Autosomal dominant
ANTICIPATION
DENIAL AIN’T JUST A RIVER IN EGYPT
-Rap song
The absence of evidence is NOT equivalent to evidence of absence
Triplet (CTG) Repeats
Repeat Expansion
Triplet Repeat Diseases
Pathogenesis of Myotonic Dystrophy
• Loss of Function– Haploinsufficiency of DMPK– Cis-chromatin effects
Cis-chromatin effects
Pathogenesis of Myotonic Dystrophy
• Loss of Function– Haploinsufficiency of DMPK– Cis-chromatin effects
• Gain of Function
Gain of Function
Ypsilanti
Demetrius Ypsilanti
Alexander Ypsilanti